Process for refining pine oleoresin



Patented Dec. 29, 1942 UNITED STATES PT T OFFEQE PROCESS FOR REFINING PINE OLEORESIN No Drawing. Application May 23, 1940, Serial No. 336,742

11 Claims.

This invention relates to a process for refining pine oleoresin and more particularly relates to a process for refining pine oleoresin so as to provide an improved gum rosin.

Pine oleoresin, as is well known, is contaminated with foreign materials which cause a discoloration or degrading of the rosin contained therein. The oleoresin contains several different types of contaminants, such as, dirt or trash, water, oxidation products and metallic impurities. The dirt or trash is in the form of pieces of bark, leaves or dust which find their way into the crude oleoresin by being washed down the side of the tree into the cup. The rain water which also Washes down the side of the tree finds its Way into the cup and contaminates the oleoresin. The crude oleoresin is also subject to oxidation in the cup, the degree to which it is oxidized being dependent on the time of exposure, thickness of film, etc.

Several methods for refining pine oleoresin and improving its color as well as removing the foreign materials have been described in the art. The crude oleoresin has been subjected to acid treatments such as with sulfuric acid and oxalic acid. The crude oleoresin has been subjected to treatment with materials such as fullers earth or animal charcoal. It has also been subjected to solvent refining procedures. These methods, however, have been open to one objection or another. Thus, while some methods have given a certain degree of refinement of the oleoresin they havenot always been successful in producing a rosin of the degree of refinement required for many uses. Furthermore, it has been necessary in most of the prior procedures to subject the crude oleoresin to treatments which generally result in a low yield of refined oleoresin r rosin and, consequently, a relatively high cost per unit.

It is an object of this invention to provide an improved process for refining pine oleoresin.

It is a further object to provide an improved process for refining pine oleoresin which is extremely simple and economical.

It is another object to provide a process for refining pine oleoresin in which ordinary plant equipment may be used.

It is still another object to provide a process of refining pine oleoresin to provide a refined F It is a still further object to provide a process of refining pine oleoresin to provide a refined rosin in a substantially quantitative yield based on the rosin content of the original pine oleoresin.

Other objects of the invention will appear hereinafter.

The above objects are accomplished in accordance with this invention by treating crude pine oleoresin under ionizing conditions with an acid salt and a metal above hydrogen in the electromotive series. The treatment is carried out under conditions which provide intimate contact between the pine oleoresin, the acid salt and the metal. As a result of the above treatment, the color of the rosin contained in the oleoresin becomes substantially lightened with practically no loss in yield and no perceptible efiect on the other physical properties.

In accordance with the process of this invention, the treatment of the pine oleoresin may be carried out on the oleoresin itself after separation of dirt, chips, etc., or on the oleoresin dissolved in a suitable organic solvent. After the treatment of the oleoresin is completed, the oleoresin solution may be washed to remove the water-soluble materials and filtered to remove the metal. The turpentine contained in the crude oleoresin and the added solvent, if one is used, may then be evaporated for the recovery of the rosin of improved color.

The crude pine oleoresin which may be treated in accordance with this invention, may be any of the various grades of oleoresin. The crude oleoresin is usually graded on the basis of the color and foreign materials contained therein. The dirt and other trash may be removed from the oleoresin by filtration, for example, before subjecting the oleoresin to the refining treatment.

As solvents for the oleoresin, any rosin solvent which is itself inert in the treatment may be employed. Crude oleoresin, as is well known, contains approximately 17% of turpentine and the remainder, except for impurities, is gum rosin. Additional turpentine may, if desired, be added to the oleoresin to provide a more dilute solution of the rosin and to facilitate the refining treatment. Other solvents may also be used. Such solvents may be for example, monocyclic aromatic hydrocarbons, such as benzol, toluol, xylol, etc.; petroleum hydrocarbons, such as, gasoline, V. M. 8: P. naphtha, hexane, heptane, etc.; hydrogenated petroleum hydrocarbons, such as those known in the trade as Solvesso solvents,

and solvents such as ethylene dichloride, carbon tetrachloride, cyclohexane, methyl cyclohexane, etc, The concentration of the rosin in the solvent is not particularly critical and may be selected so as to provide adequate workability of the solution in the process. Generally speaking, a concentration within the range of about 5% to about 85% by weight may be used, but preferably the concentration will fall in the range of about 20% to about 50% by weight based on the rosin contained in the oleoresin.

The acid salts which may be used in the process of this invention are those which contain one or more replaceable hydrogen atoms, such as, for

example sodium acid sulfate, potassium acid sulfate, mono sodium acid phosphate, disodium acid phosphate, monopotassium acid phosphate, dipotassium acid phosphate, calcium acid phosphate, lithium acid phosphate, etc.

Any of the metals above hydrogen in the electromotive series may be employed. It will be preferable, however, to use such metals which form salts having no appreciable discoloring action on the rosin contained in the oleoresin. The metals are used preferably, though not necessarily, in a finely divided form. Use of metals, as for example, cadmium, aluminum, manganese, tin and zinc is desirable. Zinc in the form of 'zinc dust, mossy zinc or zinc powder is particularly well adapted to the process.

It is desirable that at least a small amount of water or of some other ionizing solvent be present to accelerate the refining action. Thus, the acid salt maybe used in the form of a hydrate if it forms one, or in the form of an aqueous solution. Sodium acid sulfate in the form of its monohydrate is particularly desirable. Alternatively, a small amount of water or other ionizing solvent may be added. An aqueous solution containing from about 20% of the acid salt to a saturated solution of the salt at the temperature employed may be used.

It will be understood that the acid salt and the metal above hydrogen in the electromotive series are both in contact with the rosin contained in the oleoresin during the treatment. To provide satisfactory contact of the acid salt and metal with the rosin, it will be desirable to employ vigorous agitation since the refining action will be appreciably accelerated thereby.

The speed with which the oleoresin becomes refined in accordance with the process of this invention is dependent on the temperature employed in the treatment. While the treatment may be carried out at room temperature, the

A temperature within the range of about 60 C. to

about 150 C. is preferable. More preferably treatment may be carried out at about 60 C. to about 95 C. It is convenient to carry out the treatment at the reflux temperature of the solution. Where the treatment is to be carried out above the normal boiling point of the solvent, use of superatmospheric pressure is resorted to. The pressures employed are in no way limiting on the process and the equipment employed will generally determine the maximum pressure which is practical.

, The time of treatment of the oleoresin in accordance with the process of the invention may be varied to provide the resultsdesired. The time necessary to provide satisfactory refining will be dependent on such factors as the amount of color bodies present in the oleoresin, the temperature of treatment, the amount of acid salt employed, as Well as other factors. For this reason it is impossible to state any definite time necessary except in relation to a given set of conditions. The examples which follow will serve to illustrate the time of treatment which may be used in each particular case.

The amount of acid salt used may vary over a wide range depending on such factors as the particular acid salt used, the degree of refining desired, the particular conditions of treatment, as well as other factors. Considering the acid salt on an anhydrous basis, for example, ratios of rosin contained in the oleoresin to the acid salt as high as to 1 on a weight basis are practical. In general, however, ratios varying between 10 of rosin to l of acid salt down to l of rosin to l or more of the acid salt are desirable. A preferred ratio is approximately 1 of acid salt to 2 of the rosin.

The amount of metal above hydrogen in the electromotive series used is not particularly critical. It will be desirable, however, to have an amount of such metal present which will be an excess over the theoretical amount required to react with the acid salt present.

The refining treatment in accordance with the process of this invention may be carried out either in batch fashion or as a continuous process. In carrying out the treatment as a batch process, the crude oleoresin may, for example, be dissolved in the solvent in which the treatment is to be carried out to give a concentration within the range set forth above. The solution is then preferably filtered to remove bark, dirt, and other trash contained in the oleoresin. An acid salt is then added as an aqueous solution or in the form of a hydrate together with a metal above hydrogen in the electromotive series. The solution is then refluxed or agitated at an elevated tem- "perature to provide intimate contact of the ingredients. After the desired degree of refining has been obtained, the rosin solution is separated from the solution of the salt and washed several times with water to remove water-soluble reactants and other material. The washed solution may be filtered and the solvent then evaporated, preferably in an inert atmosphere to prevent any discoloration.

In carrying out the treatment in a continuous process, the crude oleoresin is dissolved as above in a suitable solvent to give a concentration within the range set forth above, and the solution then filtered to remove dirt, bark, and other trash contained in the oleoresin. The solution of oleoresin is then led to a refining vessel into which a suitable quantity of the metal above hydrogen in the electromotive series is introduced. The oleoresin solution and metal are agitated efficiently by means of an agitator and an aqueous solution of an acid salt then is pumped or flowed into the refining vessel. The temperature is raised to a point which will provide sufficient refining and maintained at that temperature until the desired degree of refining has been obtained. The refining vessel then contains a solution of refined rosin mixed with the acid salt solution and the metal. From this point on, the operation is made continuous by delivering the unrefined oleoresin solution into the bottom of the refining vessel continuously and Withdrawing from the top of the refining vessel a continuous flow of matter.

refined rosin solution, the agitation in the. refining vessel being such as to permit separation of the. refined rosin solution at the top of the vessel from the acid salt solution and the metal. The feed rate of the unrefined oleoresin solution to the refining; vessel is; adjusted at such a rate asv to provide the desired time of contact in the refining vessel between the oleoresin and the acid salt and metal. The refining solution then proceeds to. a vessel in which the solution is washed with water: to remove water-soluble. material and then passes to the filter to remove suspended The washed and. filtered refined rosin solution then passes to an evaporator of suitable type in which the volatile solvent is removed continuously under suitable conditions of temperature. and pressure. Additional aqueous solutions of the acid salt being used and additional metal are introduced to the refining vessel as required. It is preferable, to add the metal as a slurry in the, solution of the unrefined oleoresin.

As illustrative of the improved process of re fining pine oleoresin in accordance with this in vention, the examples appearing below are cited as typical of the various embodiments. colors shown in the examples are the Lovibond glass colors and are measured on V cubes of the rosin.

Example I No. 4 grade of pine oleoresin, which is a very poor grade, was dissolved in gasoline to give a solution containing approximately 20% by weight of rosin. The solution was then filtered, washed with water, filtered again and then divided into two parts. recovered by evaporation of the solvent in an atmosphere of carbon dioxide. To 250 cc. of the remaining solution, 5 grams of sodium acid sulphate monohydrate and 5 grams of zinc dust were added and the solution refluxed for about minutes. The solution was then cooled, washed with water and filtered. The rosin was recovered by evaporation of the solvent in an atmosphere of carbon dioxide. The color of the refined rosin obtained was 17 amber, which corresponds to a WW grade. The color of the rosin obtained without the refining was 120 amber plus 22 red, which corresponds to an F grade.

Example II To 250 cc. of the gasolne solution of oleoresin described in Example I, 5 grams of sodium acid sulfate monohydrate, 50 grams of water and 5 grams of zinc dust were added and the solution refluxed for approximately 20 minutes. The rosin solution was then cooled, washed with water and filtered and the rosin recovered from the solution by evaporation of the solvent in an atmosphere of carbon dioxide by heating to about 170 C. The refined rosin obtained had a color of 17 amber, which corresponds to a W grade.

Example III A poor grade of pine oleoresin was dissolved in turpentine to give a solution containing aption refluxed about 20 minutes. The refined The From the first part the rosin was 7 solution was then cooled, washed with Water and filtered. After removal of the solvent by heating to a temperature of about 170 C. in a carbon dioxide atmosphere, a refined rosin was obtained having a color of. 28 amber, which corresponds to an N grade. The color of the rosin recovered from the first part of solution without refining was 80 amber plus 30 red, which corresponds to an E grade.

Example IV A poor grade of pine oleoresin was heated to about 105 C. for about 5 minutes to melt the lumps contained therein and was then strained through cheesecloth to remove the chips and trash. The strained oleoresin was then divided into two parts and the rosin recovered from one part by evaporation of the turpentine. To 250 grams of the strained oleoresin, 5 grams of sodium acid sulfate, grams of water and 5 grams of zinc dust were added and the mixture refluxed for about 1 hour. The oleoresin was thendecanted ofi from the mixture, washed with water, filtered and the rosin recovered by evaporation of the solvent in a carbon dioxide atmoshere by heating to 170 C. The refined rosin obtained had a color of 26 amber, which corresponds to a WG grade. The color of the rosin contained in the oleoresin and recovered without refining was amber plus red, which corresponds to a D grade of rosin.

Example V A medium grade of pine oleoresin was dissolved in turpentine to give a 20% by weight solution. The solution was filtered and divided into two parts. The rosin was recovered from the first part by evaporation of the solvent by heating to a temperature of 170 C. in an atmosphere of carbon dioxide. To 250 grams of the remaining solution, 25 grams of a 20% by weight aqueous solution of primary calcium phosphate and 5 grams of zinc dust were added and the solution refluxed for about 25 minutes. The solution was then washed three times with water and the washed solution filtered. After removing the turpentine by distillation in a carbon dioxide atmosphere at a temperature up to 170 0., a refined rosin having a color of 10 amber and corresponding to an X grade was obtained. The color of the unrefined rosin separated from the oleoresin was 40 amber plus 4 red, corresponding to an H grade.

Example VI A 20% solution by weight ofmedium grade pine oleoresin in turpentine was prepared and filtered. The rosin was recovered from a part of this solution by removal of the solvent as in the other examples. Separate portions of 500 grams each of the solution were treated separately with 6 grams of zinc dust and 50 grams of a 20% solution of sodium acid sulfate in water. The treatment was carried out in each case at the reflux temperature of the solution. After the treatment was completed each solution was washed three times with gram portions of water and the rosin recovered from each solution by evaporation of the solvent. The reflux time was varied in the series of treatments. Table I below contains the details of each of the treatments and the color of the refined rosins obtained. The color of the unrefined rosin was 4.0 amber plus 1.25 red, which corresponds to a K grade.

Table I G Grams G rams rosin rams Run masin Time rosin Yield 335 5323 N o. ter master reflux rerosin rosin rosin sol. soluclaimed tion Min 1..-. 500 100 95 95 amber-- W G 2.... 500 100 104 104 26 amber WG 3.... 500 100 102 102 25 amber" WG 4.. 500 100 103 103 27 amber-- W'G 5..-. 500 60 99 99 26 amben. WG 6.... 500 100 98 98 26 ambet-. VVG 7. 500 100 60 101 101 30 ambcr-- N 8. 500 100 60 101 101 35 aInber.. N 9...- 500 100 120 99 99 40 amber- 1H 10... 500 100 99 99 40 amber. M

tained in pine oleoresin a considerable loss in yield of the rosin has always been evident.

It is to be understood that the term refining used throughout this invention refers particu- L larly to the color improvement of the rosin and not necessarily to a separation of the rosin into light-colored and dark-colored fractions.

It will also be understood that the details and examples set forth are illustrative only and that the invention as broadly described and claimed is in no way limited thereby.

What I claim and desire to protect by Letters Patent is:

l. A process for refining pine oleoresin which comprises treating pine oleoresin with an acid salt and a metal above hydrogen in the electromotive series, in the presence of an ionizing solvent for said acid salt, and at a temperature within the range of about 60 C. to about 150 C.

2. A process for refining pine oleoresin which comprises treating pine oleoresin dissolved in a. suitable solvent with an acid salt and a metal above hydrogen in the electromotive series, in the presence of an ionizing solvent for said acid salt, and at a temperature within the range of about 60 C. to about 150 C.

3. A process for refining pine oleoresin which comprises heating pin oleoresin with an acid salt and a metal above hydrogen in the electro- In previous methods of improving th color of gum rosin conmotive series, in the presence of an ionizing solvent for said acid salt, and at a temperature within the range of about 60 C. to about 150 C.

4. A process for refining pine oleoresin which comprises treating pine oleoresin dissolved in a suitable solvent with an acid salt and zinc, in the presence of an ionizing solvent for said acid salt, and at a temperature within the range of about 60 C. to about 150 C.

5. A process for refining pine oleoresin which comprises treating pine oleoresin dissolved in a suitable solvent with zinc and a hydrate of sodium acid sulfate in the presence of an ionizing solvent for the said acid salt and at a temperature within the range of about 60 C. to about 150 C.

6. A process for refining pine oleoresin which comprises treating pine oleoresin dissolved in a suitable solvent with zinc and an aqueous solution of sodium acid sulfate at a temperature within the range of about 60 C. to about 150 C.

7. A process for refining pine oleoresin which comprises heating pine oleoresin dissolved in a suitable solvent with an acid salt and a metal above hydrogen in the electromotive series in the presence of an ionizing solvent for said acid salt and at a temperature within the range of about 60 C. to about 150 C.

8. A process for refining pine oleoresin which comprises heating pine oleoresin with sodium acid sulfate and zinc in the presence of an ionizing solvent for said acid salt at a temperature within the range of about 60 C. to about 150 C.

9. A process for refining pine oleoresin which comprises heating pine oleoresin dissolved in a suitable solvent with sodium acid sulfate monohydrate and zinc at a temperature within the range of about 60 C. to about 150 C. in the presence of an ionizing solvent for the said acid sulfate.

10. A process for refining pine oleoresin which comprises heating pine oleoresin dissolved in a suitable solvent with an acid salt and a metal above hydrogen in the electromotive series in the presence of an ionizing solvent for said acid salt at a temperature within the range of about 60 C. to 150 C., washing the solution to remove water-soluble products, filtering the solution and recovering a refined gum rosin from the solution.

11. A process for refining pine oleoresin which comprises heating pine oleoresin dissolved in a suitable solvent with sodium acid sulfate and zinc in the presence of an ionizing solvent for said acid salt at a temperature Within the range of about 60 C. to 150 C., washing the solution to remove water-soluble products, filtering the solution and recovering a refined gum rosin from the solution.

WILLIAM N. TRAYLOR. 

